American Board of Internal Medicine (ABIM) Certification Practice Exam

Which class of antibiotics is preferred for intravenous treatment after a dog bite?

1. Cephalosporins

2. Macrolides

3. β-lactam/β-lactamase inhibitor combinations

4. Tetracyclines

The correct answer is: β-lactam/β-lactamase inhibitor combinations

Intravenous treatment after a dog bite primarily involves antibiotics that effectively cover the polymicrobial flora associated with dog bites, particularly Pasteurella multocida, which is commonly found in the mouths of dogs. The preferred class is the β-lactam/β-lactamase inhibitor combinations. These combinations, such as amoxicillin-clavulanate, provide broad-spectrum coverage by including β-lactam antibiotics for bacterial cell wall inhibition while also incorporating a β-lactamase inhibitor to combat resistance from bacteria that produce β-lactamase enzymes. The effectiveness against skin and soft tissue pathogens, as well as their ability to penetrate the tissues where the bite and possible infection can occur, makes them ideal for this type of wound. In contrast, other classes such as cephalosporins may not offer the same level of coverage against the specific pathogens involved in dog bites. Macrolides, while effective against some bacteria, may lack adequate efficacy against others that are typically involved in bite infections. Tetracyclines are generally used for other types of infections and may not provide the optimal coverage needed for polymicrobial dog bite wounds. Therefore, β-lactam/β-lactamase inhibitor combinations are the first-line choice in